FastCGI is a fast, open, and secure Web server interface that solves the
performance problems inherent in CGI without introducing any of the new
problems associated with writing applications to lower-level Web server APIs.

Modules to support FastCGI can be plugged into Web server APIs such as Apache
API, NSAPI, and ISAPI. Key considerations in designing FastCGI included
minimizing the cost of migrating CGI applications (including applications
written in popular scripting languages such as Perl), supporting both
single-threaded and multi-threaded application programming, supporting
distributed configurations for scaling and high availability, and generalizing
the roles that gateway applications can play beyond CGI's "responder" role.
